Mothers surrounded by green vegetation are more likely to have full term pregnancies and babies born at healthier weights compared to mothers who aren’t, the study published in Environmental Health Perspectives in October said.

Lead researcher Perry Hystad said this is an important step forward for health and environmental research.

“We know greenness is good, but this [research] is trying to say how we can use green space to advocate for health,” Hystad said.

Hystad and his OSU research team worked with the University of British Colombia, studying 64,000 births between 1999 and 2002 in Vancouver, B.C. At first, the team looked into the effects of air pollution on births, but found something surprising instead.

The team found that pregnant mothers living in neighborhoods with more trees, grass, and shrubs, saw decreases in premature births and increases in the numbers of babies born at a healthy weight.

Hystad said he suspected that the results would change once they factored in air pollution, noise levels, and the resident's better access to public health and exercise areas, but they didn’t.

Geoffrey Donovan, a research forester with the Portland Forestry Sciences Lab, said accounting for the type of people who live in heavily vegetated areas set the study apart from previous research.

Psychological and psychosocial factors could be responsible for the health benefits, but more research is needed to make sure, Hystad said.

The research team is now looking into those factors, surveying new mothers in green space areas to learn more of their social habits.

Doctor Lishiana Shaffer, an OB/GYN physician at OHSU, said full-term pregnancies and healthy baby weights are areas health professionals have been focusing on more lately.

“It’s important because those babies do so much better, have a higher chance of going home and do better in terms of feeding, sleeping, and sugar levels,” Shaffer said.

Planning for the Future

Whatever the cause, Hystad said the findings are something that city planners should consider for future policy.

“It’s a really interesting new venue for research, specifically in environmental health,” Hystad said. “It’s something that’s relatively easy to modify and there's a lot of co-benefits that go along with it.”

Portland’s tree canopy covers almost 30 percent of the city, a 2.6 percent increase over the last 10 years, according to the Portland Parks and Recreation Department.